Unexpected MySQL DATETIME behavior

Question

I'm seeing what seems to me unexpected behavior from MySQL DATETIME when I'm trying to insert values into my table from my Java application. I've read a lot of StackOverflow questions and answers regarding DATETIME, but this seems to be a totally different issue.

My Java application uses MyBatis and this DateTimeTypeHandler to insert a joda DateTime value 2015-03-04T22:30:59.922Z . (I also modified the above code to use the setTimestamp(int, Timestamp, Calendar) method but did not notice and difference in results).

What I see being inserted into the table is the value 2015-03-04 14:30:59.922 . I read that MySQL DATETIME uses the server default timezone. I live in the PDT timezone so I would expect the value to be 2015-03-04 15:30:59.922 (that's 15:30 instead of 14:30).

What's surprising is nothing in MySQL seems to indicate the PDT timezone. So why would my datetime value in the table be 2015-03-04 14:30:59.922?

mysql> select @@global.time_zone; +--------------------+ | @@global.time_zone | +--------------------+ | UTC | +--------------------+ 1 row in set (0.06 sec)

mysql> select @@session.time_zone; +---------------------+ | @@session.time_zone | +---------------------+ | UTC | +---------------------+ 1 row in set (0.07 sec)

mysql> SELECT @@system_time_zone; +--------------------+ | @@system_time_zone | +--------------------+ | UTC | +--------------------+ 1 row in set (0.07 sec)

Answer 1

March 4, 2015 was Standard time so the offset is -8 hours:

UTC (Time Zone)                   Wednesday, March 4, 2015 at 10:30:00 PM     UTC         
Los Angeles (U.S.A. - California) Wednesday, March 4, 2015 at 2:30:00 PM  PST UTC-8 hours 

Today (May 28, 2015) is Daylight time so the offset is -7 hours:

UTC (Time Zone)                   Thursday, May 28, 2015 at 10:30:00 PM     UTC         
Los Angeles (U.S.A. - California) Thursday, May 28, 2015 at 3:30:00 PM  PDT UTC-7 hours